1. Field of the Invention
The present invention relates to a display device and a method of driving the same. More particularly, the present invention relates to a display device for providing a charge discharged from data lines to a battery and a method of driving the same.
2. Description of the Related Art
A display device displays a certain image, and especially an organic electroluminescent device is a self light emitting device.
FIG. 1 is a view illustrating a common display device.
In FIG. 1, the display device includes a panel 100, a controller 102, a first scan driving circuit 104, a second scan driving circuit 106, a discharging circuit 108, a precharging circuit 110, a data driving circuit 112, a battery 114 and a DC-DC circuit 116.
The panel 100 includes a plurality of pixels E11 to E44 formed in cross areas of data lines D1 to D4 and scan lines S1 to S4.
The controller 102 receives display data from an outside apparatus (not shown), and controls the scan driving circuits 104 and 106, the precharging circuit 110, and the data driving circuit 112 by using the received display data.
The first scan driving circuit 104 transmits first scan signals to some of the scan lines S1 to S4, e.g. S1 and S3 under control of the controller 102.
The second scan driving circuit 106 transmits second scan signals to the other scan lines S2 and S4 under control of the controller 102. As a result, the scan lines S1 to S4 are connected in sequence to a ground.
The discharging circuit 108 has switches SW1 to SW4 and a zener diode ZD, and discharges the data lines D1 to D4 up to the voltage of the zener diode ZD during a discharge time.
The precharging circuit 110 provides precharge currents corresponding to the display data to the data lines D1 to D4 under control of the controller 102, thereby precharging the data lines D1 to D4.
The data driving circuit 112 includes a plurality of current sources IS1 to IS4, and provides data currents corresponding to the display data and outputted from the current sources IS1 to IS4 to the data lines D1 to D4 under control of the controller 102. As a result, the pixels E11 to E44 emit light.
The DC-DC circuit 116 boosts a battery voltage outputted from the battery 114 up to a driving voltage Vcc, and then outputs the boosted battery voltage.
FIG. 2A and FIG. 2B are views illustrating the process of driving the display device of FIG. 1. FIG. 2C is a timing diagram illustrating the process of driving the display device.
In FIG. 2A and FIG. 2C, the switches SW1 to SW4 are turned on, and the scan lines S1 to S4 are connected to a non-luminescent source having the same voltage V2 as the driving voltage Vcc. As a result, the data lines D1 to D4 are discharged up to the voltage of the zener diode ZD during a first discharge time dcha1.
Subsequently, the precharge circuit 110 provides precharge currents to the data lines D1 to D4 during a first precharge time pcha1, thereby precharging the discharged data lines D1 to D4.
Then, the first scan line S1 is connected to the ground as shown in FIG. 2A, and the other scan lines S2 to S4 are connected to the non-luminescent source. In addition, the switches SW1 to SW4 are turned off.
Subsequently, the data driving circuit 112 provides data currents I11 to I41 corresponding to first display data to the precharged data lines D1 to D4 during a first luminescent time t1. In this case, the data currents I11 to I41 are passed to the ground through the data lines D1 to D4, the pixels E11 to E41, and the first scan line S1. As a result, the pixels E11 to E41 related to the first scan line S1 emit light.
Then, the switches SW1 to SW4 are turned on during a second discharge time dcha2, and the scan lines S1 to S4 are connected to the non-luminescent source. As a result, the data lines D1 to D4 are discharged to the voltage of the zener diode ZD.
Subsequently, the precharging circuit 110 provides precharge currents to the discharged data lines D1 to D4 during a second precharge time pcha2, thereby precharging the discharged data lines D1 to D4.
Then, a second scan line S2 is connected to the ground, and the other scan lines S1, S3 and S4 are connected to the non-luminescent source. Additionally, the switches SW1 to SW4 are turned off.
Then, the data driving circuit 112 provides data currents I12 to I42 corresponding to second display data to the precharged data lines D1 to D4 during a second luminescent time t2 as shown in FIG. 2B, wherein the second display data is inputted to the controller 102 after the first display data is inputted to the controller 102. In this case, the data currents I12 to I42 are passed to the ground through the data lines D1 to D4, the pixels E12 to E42, and the second scan line S2. As a result, the pixels E12 to E42 related to the second scan line S2 emit light.
Pixels E13 to E43 corresponding to a third scan line S3 emit light through the method described above, and then pixels E14 to E44 corresponding to a fourth scan line S4 emit light. Subsequently, the above process of emitting light in the pixels E11 to E44 is repeated as one unit of the scan lines S1 to S4, i.e. a frame.
As described above, the data lines D1 to D4 are discharged up to a certain discharging voltage during a discharge time, i.e. electric charges charged to the data lines D1 to D4 are discharged and consumed. Thus, the battery 114 is consumed a lot, and accordingly, the power consumption of the display device becomes high.